A wearable, sweat-sensing patch that can monitor and regulate blood glucose levels is described in a paper published online this week in Nature Nanotechnology. The graphene-based patch is shown to deliver metformin, a drug used to treat diabetes, through the skin to reduce high blood glucose levels in diabetic mice.
A minimally- or non-invasive method for monitoring blood glucose levels in diabetes is much sought after, and detecting glucose in sweat is a potential alternative to finger pricking, which can be painful and has low patient compliance. Graphene shows promise for use in wearable electronics as it is flexible, conducts electricity, and can be transparent, soft and very thin. However, the way that it is synthesized limits its use in electrochemical devices for the detection of biochemical markers, such as pH, ions, and biomolecules.
Dae-Hyeong Kim and colleagues added gold particles to graphene and combined it with a gold mesh to create a flexible, semi-transparent patch and demonstrated its potential for diabetes monitoring and feedback therapy in diabetic mice and two healthy human males. The patch contains a variety of sensors that detect humidity, glucose, pH and temperature. Because the enzyme-based glucose sensor is affected by pH changes in sweat, the pH and temperature sensors correct the glucose measurements by taking into account pH and temperature in real time, improving its reliability. Finally, when the patch senses a high glucose concentration in sweat, heaters embedded in the patch trigger microneedles to dissolve their coat and release the drug metformin. The authors note that the drug delivery components of the patch will need to be scaled up before the patch can be trialled with human patients.
In an accompanying News & Views article, Richard Guy writes: “…although the holy grail of diabetes management - a non-invasive feedback system combining glucose monitoring and responsive drug delivery - is not yet at hand, Kim and co-workers have certainly moved the field closer to this coveted prize.”